It's explained through the topic, but basically whenever you put in a bet, you are placed in a queue. A person in line will get paid double once enough people after him put up enough bets to pay out double of what he invested. Then it moves to the next person in line.

As you play, it takes longer and longer to get your double just because you are hoping to get everyone else to pay for your bet. I got tired of waiting, so I put down money against myself hoping to break even and keep the game rolling so other people had a chance to play, but the guy who started the game took the weekend off.